ZnO:Al Thin Film Deposited By Chemical Bath And Its Application In CZTS Battery

A new kind of semiconductor material—transparent conductive film came into being with the continuously development of computer,touch screen,solar cells,liquid crystal display and other fields.As the transparent electrode of solar cells,transparent conductive film is very important for improving the photoelectric conversion efficiency of the cell.Compared with ITO thin films,AZO films have advantages such as non-toxic,wide sources and more stability in hydrogen plasma.The preparation of AZO thin film by solution method is cheap,simple and environment-friendly,and the research is of great value.Based on the above background,AZO transparent conductive films were prepared by chemical bath deposition method.A dense zinc oxide thin film was obtained by depositing seed layer on the substrate and then subjecting it to a water bath at a constant temperature.It was found that the preparation of seed layer and the deposition process parameters of the aqueous solution have important effects on the final morphology of the zinc oxide film.The heat treatment temperature of the seed layer,solution concentration and the number of spin coating would influence the thickness,uniformity and adhesion of the seed layer.The deposition temperature would affect the growth rate,crystal orientation and grain size of zinc oxide nanorods.The concentration of zinc oxide in aqueous solution has obvious effect on the structure,density and growth rate of nanorods.Ammonium citrate will promote the lateral growth of zinc oxide nanorods.The zinc oxide thin film with uniform crystal orientation,compact structure and uniform grain size could be achieved by adding ammonium citrate to the solution,this will directly affect the resistivity of the film.The most even and smooth seed layer was achieved by sol-gel method,at the condition of the solution concentration of 0.5 mmol/L,heat treatment temperature of 250 ?,and spin-coated for twice.When the deposition temperature was 80 ?,the concentration of zinc oxide was 38 mmol/L and the concentration of ammonium citrate was 2 mmol/L,the crystal morphology of the film was the best and the resistivity was the lowest.In this research,the zinc oxide films were doped by aluminum sheet or aluminum nitrate nonahydrate solution,respectively.It was found that the area of the aluminum sheet,the pH value of the solution and the growth time of the thin film have an important impact on the electrical properties of the film when aluminum sheet was the aluminum source.The concentration of aluminum nitrate nonahydrate and the growth time of the film were the most important factors in the process of doping with aluminum nitrate solution.The resistivity of AZO thin films could be reduced to 10-2 by UV irradiation.Finally,the thin film was deposited on the surface of CZTS thin film solar cell,and the photoelectric conversion efficiency and external quantum efficiency of the solar cell were measured.The photoelectric conversion efficiency(?)of the battery can reach 5.47%,with the open circuit voltage(Voc)of the cell was 625 m V(Voc),the short circuit current(Jsc)was equal to 16.43 m A/cm2,and the fill factor(FF)was 53.4%.The results showed that the AZO thin films prepared by chemical bath deposition and doped with aluminum sheet can meet the requirements of CZTS solar cells.